Coding keyboard and electrical switch therefor

ABSTRACT

A keyboard for electronic apparatus such as computer and communication equipment, and an electrical switch therefor including a resilient deformable tube filled with an electrically conductive liquid such as mercury. Included in the keyboard is an elongated conductive means comprising a plurality of side-by-side conductors. The keyboard switch modules are each provided with a plurality of contact elements and mounting means adapted for holding the contact elements in anyone of a plurality of predetermined positions whereby each switch module can be encoded and thus preconditioned for electrically energizing a different preselected combination of the conductors to represent the desired code data unique to each switch.

United States Patent Twyford 1 Dec. 26, 1972 541 CODING KEYBOARD AND3,494,550 2/1970 Hayes et al ..200/159B ELECTRICAL SWITCH THEREFOR 221;; l----- /152.9 3,360,6 Nic e son ZOO/152.9 Wanton W Falls Church3,536,932 10/1970 Humbert-Droz ..307/106 [73] Assignee: MechanicalEnterprises lncor- Primary f' Hohauscl' pol-ted Attorney-Birch,Swindler, McKie & Beckett [21] P'' 76496 A keyboard for electronicapparatus such as computer n ted A union and communication equipment,and an electrical e a pp switch therefor including 'a resilientdeformable tube C0"lifluaiion-in-lli"t 0f S66Y488- 15, filled with anelectrically conductive liquid such as 1969- mercury. included in thekeyboard is an elongated conductive means comprising a plurality ofside-by- [52] U.S.Cl. ..200/211,200/l88, 200/5 E, Side conductors. Thekeyboard switch modules are gg g g each provided with a plurality ofcontact elements and [51] i 2 B E mounting means adapted for holding thecontact ele- [58] held M 87 88 3 ments in anyone of a plurality ofpredetermined posil tions whereby each switch module can be encoded andthus preconditioned for electrically energizing a [56] References cueddifferent preselected combination of the conductors to UNITED-STATESPATENTS represent the desired code data unique to each switch.

3,591,749 7/1971 Comstock .,200/159 B 28 Claims, 11 Drawing FiguresPATENTED DEC 2 6 m2 SHEET 1 BF 4 m mm E WH m PATENTEDBEBZB m2 3,707.61 1

saw 2 [1F 4 INVENTOR ROBERT H TWYFORD PATENTED E I972 3.707.611

sum 3 or 4 Q PATENTEUnEc 26 m2 SHEET [If 4 FIG. 8

CODING KEYBOARD AND ELECTRICAL SWITCH THEREFOR PRIOR APPLICATION This isa continuation in part of application Ser. No. 866,488, filed Oct. '1 5,1969.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to the field of electric switch keyboards, such as findextensive use in the computer and related industries. Further theinvention is concerned with electrical switches and encoded switchmodules particularly adapted for arrangement and use in such keyboards.

2. Description of the Prior Art The computer and related data processingindustries offer many applications for keyboards. The cost of suchkeyboards has become a significant factor with the large volumerequirements for keyboards in remote terminals, input devices and otherperipheral equipment used in computer and data processing applications.

A variety of electrical switch designs for such keyboards, to generatethe requisite coded signals, have been proposed. These have ranged frommechanical electrical switch concepts through electronic switchingproposals. In all such designs, low initial investment and maintenancefree operation with high operational reliability are prime requisites. Aparticular requirement for a satisfactory keyboard switch is one whereinclosure of the electrical circuit occurs with a bounce free response.Such bounce free circuit closing is characterized by creation of a cleanelectrical signal wherein a non-erratic rise from one voltage level toanother occurs when the switch is closed by depression of the key on thekeyboard connected to actuate the switch.

In electric switch keyboards, coded electrical signals must betransmitted rapidly with precise accuracy in sending data from say aremote terminal to a computer location. This requires a bounce freeswitch closure for operation of the various solid state circuits mostfrequently involved in utilization of the coded data. Upon depression ofa key on the keyboard and consequent closure of the switch operated bythe key, a clean shift from one voltage condition to another, with aclean change in the voltage level must occur.

The inability to obtain the perfection required in keyboard switches hasnecessitated utilization of additional components in the form of bouncegates or delay circuits so that the undesired, unclean or flutteringclosure of the electrical circuit is blanked out to be prevented frominterfering with proper operation of the solid state circuits controlledby the coded electrical signal data. Of course, the necessity for addingbounce gates and delay circuits, broughtabout by the inability toachieve a bounce free switch response, adds to the cost of'the keyboardand related equipment.

In seeking to achieve the ideal of a bounce free" keyboard. switch, theprior art has shied away from metalto metal contact switches, which arequite prone to produce an unclean fluttering or bouncing closure of anelectrical circuit. In doing this various, highly refined and elaborateelectronic switching proposals have been developed and incorporated inkeyboard construction. These approaches can be expensive and complex intheir solutions to the problem of generating clean, coded, electricalsignal data and frequently, lack the flexibility for make up of akeyboard which will meet the wide variety of applications in thecomputer and data handling fields.

SUMMARY OF THE INVENTION It is a principal object of the invention toprovide a miniaturized manually actuatable electrical switchparticularly capable of being utilized in electrically coded datatransposing equipment, such as keyboards used in the computer and dataprocessing fields.

An adjunct and further primary aim of the invention is to provide aswitch module, for keyboard applications mentioned in the above object,capableof being readily and easily preconditioned or encoded so as to beable, upon closure, to produce and transmit particular coded electricalsignals in the form of data unique to the encoding of the switch.

Another very important object of the invention is to provide anelectrical switch capable of producing a bounce free" electrical signalwherein a clean, non-erratic change from one voltage level to anothercharacterizes the signal generated upon switch closure.

The invention also has as its object to provide a key operated switchpossessing the advantages of the above recited object wherein switchactuation is accompanied by improved touch or feel in depressing andreleasing the switch key while long switch life is achieved.

A further important object of the invention is to provide an electricalswitch module for use in keyboard applications wherein each switch forthe keyboard is completely encoded, independently of other keyboardswitches, and the individual switches are capable of being employed at amultitude of different keyboard'locations and not limited to use at asingle keyboard location.

A further object is to provide a switch module, adapted for the abovementioned keyboard applications, wherein such module embodies solidstate encoding with only one switch contact circuit being opened andclosed in actuation of the switch for each module.

It is also an object of the instant invention to provide a switch moduleparticularly suited for electronic keyboard equipment wherein theencoding for the switch to represent desired unique code data can bereadily changed as may be desired without the necessity of interruptingsemipermanent junctures such as soldered connections.

A further object of the invention is to provide an electric switchkeyboard wherein reduced cost is achieved as by avoiding use offrequently used printed circuit boards and wherein the keyboard ischaracterized by complete versatility to enable making up differentkeyboards with many different key locations to meet the variety of needsfor keyboards in the computer and data processing fields.

The foregoing objects, aims and purposes of the invention aresubstantially met and the shortcomings of the prior art aresubstantially alleviated through the use of. the present invention whichin one aspect includes a switch comprising an elongated, deformable,resilient tube; an electrically conductive liquid substantially fillingsaid tube; and an actuator including a tube contacting edge portionoperable to laterally displace at least a central segment of the tubesufficiently far to crimp said segment of the tube across said portionwhereby to pinch the liquid and open an electrical circuit. Thus isprovided an efficient, inexpensive, normally electrically open switchhaving extremely simple mechanical construction.

In another aspect, the invention includes an encoded push button switchmodule adapted for transmitting a preselected coded combination ofelectrical signals to an electrically conductive means comprising aplurality of elongated side-by-side electrical conductors. In thisaspect of the invention the switch comprises a pair of electricalcontacts and a switching mechanism including a manually operatedactuator operable to make and break and electrical circuit between thecontacts. Also included are a number of elongated contact elements and acontact element mounting member having a plurality of elongated contactelement receiving openings extending therethrough. The openings arerelatively disposed for simultaneous alignment with correspondingconductors. Contact elements are disposed in only certain of theopenings corresponding to the desired preselected encoding combinationrequired to represent the code data unique to each switch. Also includedis an electrically conductive member mounted on the mounting member. Theconductive member is provided with a plurality of resilient extensions,a respective one of which projects across one end of each of theopenings in disposition for yieldably contacting, in electrical currenttransmitting relationship, the proximal end of a contact element in theopening. Thus, the contact element is yieldably urged in the directionof its opposite end and into electrical current transmittingrelationship relative to a corresponding conductor. One of the contactsof the switching mechanism is disposed in electrical currenttransmitting relationship relative to the conductive member while theother contact of the switching mechanism is disposed for contacting oneof the conductors in current transmitting relationship therewith. Thusis provided a unitary encoded switch module which can be readilyincorporated onto an electronic keyboard.

In yet another aspect, the invention includes an electrical keyboardwhich includes a frame; an elongated electrical conducting meansincluding a plurality of elongated, generally parallel, laterally spacedconductors, said conducting means being mounted on the frame; and atleast one push-button switch mounted on the frame adjacent theconducting means, said switch including an electrical contact, at leastone electrical contact element, means for yieldably biasing the contactelement toward a corresponding one of the conductors and into electricalcurrent transmitting connection therewith, and a switching mechanismoperable to make and break an electrical circuit between said contactand said contact element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially explodedperspective view of an electronic keyboard which embodies the conceptsand principles of the instant invention;

FIG. 2 is an exploded perspective view of an electric switch whichembodies the concepts and principles of the invention, certain portionsof the switch housing having been cutaway to expose internal details;

FIG. 3 is a perspective view of the contact element mounting member ofthe switch having the electrically conductive element biasing structuremounted thereon;

FIG. 4 is an enlarged cross-sectional view of the switch of FIG. 2 inits normal, electrically open condition;

FIG. 5 is a cross-sectional view of the switch in its actuated,electrically closed condition;

FIG. 6 is a cross-sectional view taken substantially along line 6-6 ofFIG. 4;

FIG. 7 is a cross-sectional view taken substantially along line 7-7 ofFIG. 5;

FIG. 8 is a cross-sectional view taken substantially along line 8-8 ofFIG. 4;

FIG. 9 is a partial cross-sectional view embodiment;

FIG. 10 is an exploded perspective view of the upper end of the switchhousing illustrating the alternate embodiment of FIG. 9; and

FIG. 11 is a partial cross-sectional view similar to FIG. 4 but showingan alternate improved switch embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT I An electrical devicein the nature of a keyboard for an electronic computer or thelike isillustrated in FIG. 1 and is broadly designated by the numeral 20.Keyboard 20, which embodies the principles and concepts of theinvention, includes a frame 22 and a plurality of push-button switches24. Incidentally, FIG. 1 is a partially exploded view of a keyboardwhich would have 10 switches 24 such as utilized in the keyboard of aten key adding machine or calculator. However, it is to be understoodthat the board could have any desired number of switches as may berequired.

Each of the switches 24 for keyboard 20 includes a housing 26 having acavity 28 extending therethrough. Housing 26, including its mountingbase 30, is preferably formed in one piece from a moldable,thermoplastic resin, such as for example, polycarbonate resin or thelike. It is to be appreciated, however, that the material ofconstruction of housing 26 is not critical and other suitable materialsare well-known to the routineer in this art.

Cavity 28 is defined within housing 26 by opposed side walls 32, opposedend walls 34 and a lower wall 36. Opposed grooves 38 formed in end walls34 are aligned with a slot 40 in lower wall 36. A shoulder 25 isprovided on the underside of base 30. Shoulder 2S completely surroundsslot 40 and extends in parallelism therewith from one side of base 30 tothe other. Thus is presented a pair of spaced indentations 27 disposedin opposed relationship on opposite sides of shoulder 25.

An actuator 42 is received within cavity 28 with its opposed sides 44slideably disposed within grooves 38, the latter thereby establishing apath through cavity 28 upon which actuator 42 is reciprocable. Actuator42 has an elongated slot 43 therein adapted for alignment with a pair ofholes 45 in housing 26. A pin 47 extends through holes 45 and slot 43 tolimit the extent of reciprocable movement of actuator 42.

A tube 46 constructed of deformable and resilient material, such asrubber, plastic, or some other like elastomer, is positioned to extendthrough cavity 28.

of an alternate Preferably, tube 46 will be disposed in a U-shapedconfiguration with the central segment 48 and the bight 50 thereofextending upwardly through slot 40 into cavity 28. Tube 46 willgenerally be substantially filled with an electrically conductive,non-wetting liquid, such as, for example, mercury. One end of tube 46 isclosed with a contact 52 while the other end of the tube is closed witha contact 54, contacts 52 and 54 being disposed in contactingrelationship relative to the liquid within tube 46.

A sleeve 56 is secured onto each end of tube 46 adjacent contacts 52 and54 respectively. Sleeves 56 are slightly larger in diameter than thewidth of slot 40 for a purpose to be explained hereinbelow. When tube 46and actuator 42 are disposed within cavity 28, the bight 50 of tube 46is disposed around a tube contacting edge portion in the nature of aknife edge 58 formed on actuator 42. In this regard, bight 50 extendsbetween knife edge 58 and a second; more rounded tube contacting portion60 also formed on actuator 42.

An upper extension 62 on actuator 42 projects externally of housing 26and mounts thereon a manually engageable element in the nature of anindicia displaying push button 64. A coil spring 66 is disposed betweenthe upper surface 68 of base 30 and push button 64 for yieldably biasingpush button 64 away from mounting base 30. Thus, actuator 42 is urgedupwardly along its path of reciprocation which extends through cavity 28and generally laterally to one side of tube 46. Accordingly, actuator 42is yieldably biased into its tube crimping position illustrated in FIGS.4 and 8. In this position, segment 48 of tube 46 has been displacedsufficiently far that the same is crimped and pinched as it is stretchedover knife edge 58 whereby the liquid in tube 46 is parted. It should benoted that tube 46 is stretched across edge 58 because sleeves 56 arelarger in diameter than slot 40 and therefore the ends of tube 46 areheld against upward movement. Whereas edge 58 is shown as having arelatively sharp configuration it will be appreciated that this edge maybe blunted or more rounded to. achieve some increase in the life of tube46.'I-Iowever, with a sharp edge 58 the switch is less sensitive toaccidental closing of the circuit.

In operation, spring 66 biases actuator 42 into its tube crimpingposition illustrated in FIGS. 4 and 8. In this position, tube 46 iscrimped across knife edge 58 and is pinched to part the liquid therein.Accordingly, switch 24 is normally disposed in an electrically opencondition. When push button 64 is manually forced downwardly against thebias of spring 66, knife edge 58 is moved downwardly until tube 46 isreleased whereby switch 24 assumes its tube releasing positionillustrated in FIGS. 5 and 9. In this latter position, the resilience oftube 46 will cause central segment 48 and bight 50 thereof to assumetheir normal cylindrical shape whereby the liquid in the tube willbecome joined so that an electrical current can be transmitted betweencontacts 52 and 54.

As push button 64 is actuated, and as knife edge 58 moves downwardly,the upper tube contacting portion 60 of actuator 42 will contact thecrimped portion at the bight 50 of tube 56 to thereby assist in removingthe crimp created when knife edge 58 was in its upper position. Thisaction provides an extremely'quick response.

Mounting base 30 is provided with four support legs 70. Legs 70 arecantilevered downwardly from the corners of base 30 and each has asmallprotrusion 72 thereon for a purpose to be described below.

A contact element mounting member in the nature of a block 74 isprovided for supporting a plurality of elongated contact elements 76 and78. Block 74 may preferably be constructed of the same material ashousing 26 and is provided with a plurality of contact element receivingopenings which extend therethrough. Viewing FIG. 8, it can be seen thateach opening 80 is provided with a shoulder 82 at the lower end thereoffor supporting elements 76 and 78 during assembly. Thus, each opening 80has a lower portion 81 of reduced size surrounded by shoulder 82.

Switches 24 are particularly adapted for use with an electricalconducting means 84 comprising a backing strip 86 and a plurality ofelongated, generally parallel, side-by-side conductors 88. For "thispurpose, the openings 80 through block 74 are disposed in substantiallyparallel relationship for simultaneous alignment with corresponding ofthe conductors 88. That is to say, when block 74 is disposed in itsoperational relationship relative to conducting means 84, a respectiveconductor 88 is disposed directly in line with and beneath each opening80.

The switches 24 most generally will be used with direct current. Thus,elements 76 and 78 preferably comprise diodes to prevent reverse flow ofcurrent when various combinations of the conductors are connected byclosing a switch 24. In this regard, element 78 preferably includes aresistor 78a as well as a diode 78b for a purpose to be described below.In any event, elements 76 and 78 are slightly longer than the openings80. Further, each includes a lower extension 90 which is longer thanportions 81 of holes 80 and which is disposed to project outwardly ofblock 74 when elements 76 and 78 are disposed within openings 80.Elements 76 and 78 each also have an upper extension 92 disposed toproject outwardly of openings 80 at the opposite end thereof from lowerextension 90.

An electrically conductive structure in the nature of a currentdistributor 94 is mounted on body 74. Distributor 94 may preferably beformed from a copperberyllium alloy and includes a generally U-shapedcentral strap 96 having a short leg 98, a long leg 100, and a bight 102interconnecting legs 98 and 100. Distributor 94 also includes aplurality of resilient extensions 104 which project laterally outwardlyfrom leg 100. An alignment hole 106 is provided in leg for impalement ona corresponding alignment peg 108 on block 74. Distributor 94 is alsoprovided with a hole 110 in leg 98 adapted for alignment with a threadedhole 112 in block 74. Thus, distributor 94 may be securely held in placeon block 74 by a screw 114 received through hole 110 and threadablyengaged within threaded hole 112. Manifestly, other means for attachingdistributor 94 to block 74 will be apparent to those skilled in the art.

, When distributor 94 is properly in place on block 74 with peg 108projecting through hole 106 and with screw 114 extending through hole110 and into hole 112, a respective resilient extension 104 projectsacross the upper end of each opening 80. Extensions 104 are disposed foryieldably contacting, in electrical current transmitting relationship,the upper extension 92 of a contact element 76 or 78 disposed within acorresponding opening 80. Accordingly, since elements 76 and 78 arelonger than openings 80, and since lower extensions 90 are longer thanreduced portions 81 of openings 80, extension 104 urge elements 76 and78 in the direction of their lower extension 90. Hence, when block 74 isdisposed in operational relationship relative to conducting means 84,contact elements 76 and 78 will be yieldably biased toward correspondingconductors 88.

An elongated opening 116 in leg 100 of distributor 94 is disposed toexpose a pair of side-by-side openings 118 and 120 which extend throughblock 74 in general parallelism with openings 80. Block 74 also has apair of openings 122 extending therethrough for alignment withcorresponding threaded openings 124 in mounting base 30. Accordingly,block 74 is attached to the underside of base 30 by a pair of screws 126which extend through openings 122 and into openings 124. It is to benoted that shoulder 25 bears directly on leg 100 of distributor 94 andindentations 27 provide space for proper functioning of extensions 104.In this connection, an alignment hole 127 is provided in shoulder 25 inposition to receive alignment peg 108 therein.

When block 74 is mounted on the underside of base 30, openings 118 and120 are in alignment with slot 40. Further, openings 118 and 120 aresized to receive sleeves 56 of tube 46 therein. Also, it is to be notedthat leg 98 of distributor 94 is disposed directly beneath opening 118.Contact 52 is received within opening 118, and contact 52 and itscorresponding sleeve 56 are slightly longer than opening 118 so thatcontact 52 will press against leg 98 in electrical current transmittingrelationship thereto. In this connection, as is best illustrated in FIG.4, leg 98 is yieldably forced downwardly by contact 52 whereby apositive pressure is maintained between leg 98 and contact 52.

Contact 54 and its corresponding sleeve 56 are disposed within opening120. Opening 120, like openings 80, is disposed for alignment with oneof the conductors 88a adapted for serving as a common conductor toprovide simultaneously a source of electrical current for a plurality ofswitches 24. Manifestly, contact 54 and .its corresponding sleeve 56must be sufficiently long to connect with conductor 88a in electricalcurrent transmitting relationship thereto.

Elements 76 and 78 are preferably disposed in only I certain preselectedopenings 80 corresponding to a predetermined coded combinationelectrical signal which represents the desired code data unique to eachswitch. For example, with openings 80 as illustrated, switch 24 iscapable of transmitting 2,048 different binary encoded charactersrepresented by electrical signals. In this regard, it is to berecognized that the signal may be established by energizing anycombination of one or more of the conductors 88. Manifestly, extensions92 of contact elements 76 and 78 are all contacted by distributor 94 andtherefore the elements 76 and 78 are all connected in parallelelectrical relationship.

As discussed above, a plurality of switches 24 are mounted on frame 22to present keyboard 20. Frame 22 has a stair-step configurationproviding a plurality of steps 128 separated by risers 130. Steps 128are separated by walls 132 extending upwardly from corresponding risers130. Also, a similar wall 134 is provided on the outboard side of theuppermost step 128 while a wall 135 is provided on the outboard side ofthe lowermost step 128. A groove 136 extends longitudinally of wall 134and of each riser 130. A corresponding groove 138 extends longitudinallyof wall 135 and of each wall 132. Grooves 136 are thus disposed inopposed, generally parallel relation relative to corresponding grooves138 on opposite sides of each step 128.

Conducting means 84 may preferably be in the form of an elongated tapeprovided with an adhesive, such as a pressure sensitive backing, on theopposite side of backing 86 from conductors 88. Thus, tape 84 may beinstalled to extend along one step 128, back along the next higher step128, etc., as best illustrated in FIG. 1. At the end of each step thetape 84 is folded through two successive 45 bends to continue back alongthe next higher step. In this connection it is to be noted that therelative positions ofconductors 88 are reversed on adjacent steps 128.That is to say, the conductor 88 which is closest to wall 132 on thelowermost step 128, will also be closest to the same wall 132 as tape 84extends in the opposite direction along the next higher step 128. Sincethe relative positions of the conductors 88 are reversed on adjacentsteps 128 of frame 22, the disposition ofswitches 24 must also bereversed so that the elements 76 and 78 remain in proper dispositionrelative to conductors 88. After, conducting means 84 is installed,lengths of insulating tape 133 may be provided to cover the bent overends 135 of the conducting means 84.

Grooves 136 and 138 are disposed for snappingly receiving thereinprotrusions 72 of legs on each switch 24. In this regard, legs 70 aresufficiently resilient so that switches 24 may be readily snapped intoplace between the opposed facing surfaces of opposed walls 132.

Contact element 78 composed of a combination of resistor 78a and diode78b is adapted for serving a special purpose. This type element willpreferably be disposed in the same opening in each block 74'for switches24. That is to say, element 78 will be disposed in the upper left handopening 80a (See FIG. 2) of each of the switches. 24 of the keyboard 20.Openings 80a are disposed in alignment with a conductor 88b which willtherefore serve as a common conductor for all of the elements 78. Hence,if two or more switches 24 are actuated simultaneously, the electricalcurrent characteristics in conductor 88b will be different than whenonly a single switch 24 is actuated and this difference can be detectedand used to reject such signals representing the improper actuation ofmore than one switch 24 at any one time.

Switches 24 may each be provided with an overcenter device adapted togive the operator of keyboard 20 a better feel in depressing eachswitch. This device gives a sensation of a snap action when each switchis depressed. This device, which preferably takes the form of atransversely bowed cricket spring 140 (FIGS. 9 and 10), is adapted forcausing the resistance acting against push button 64 during operation ofswitch 24 to change at the moment that the crimp in tube 46 is releasedto open an electrical circuit. Spring 140 is preferably mounted on a peg141 to extend across the upper end of cavity 28 and through slot 43 ofactuator element 42. As push button 64 is depressed, the upper end 43aof slot 43 contacts spring 140 and therefore spring 140 yieldablyresists the movement of actuator 42 as the latter moves downwardly. Thebow transversely of the length of spring 140 initially resists downwardmovement of actuator 42 with a stronger force than such spring offerswhen the bowed form snaps flat as actuator is pressed further down.Spring 140 should preferably be positioned relative to end 430 such thatspring 140 will pass its central or snap" point and collapse atapproximately the same time that the crimp in the tube 46 is released.Thus, the change in resistance to movement of push button 64 will informan operator that the coded signal unique to the actuated switch has beentransmitted.

Referring to FIG. 11, this partial cross-sectional view illustrates animproved switch embodiment incorporating many of the featurescharacteristic of the switches heretofore described while embodying anactuator having a perfected tube contacting edge portion for crimpingthe mercury filled resilient tube. This switch embodiment alsoincorporatesstructure to better contain and utilize the biasing force ofthe spring which normally retains the switch in its open circuitcondition.

As in the previously described switches 24, useable with keyboard 20,the switch embodiment shown in FIG. 11 includes a housing 26 providedwith a cavity 28. The cavity 28 is defined by opposed side walls,opposed end walls and a lower wall with opposed grooves 38 formed in theend walls of the cavity similar to the construction of the previouslydescribed switch embodiments. An actuator 42 is slideably disposedwithin grooves 38 to be reciprocable therein. A deformable resilienttube 46 filled with an electrically conductive, non-wetting liquid suchas mercury is mounted in a U- shaped configuration with a centralsegment 48 and the bight 50 thereof extending upwardly into the cavity28, all as characteristic of the switches previously described.

The actuator 42 is provided with an upper extension 62 and an indiciadisplaying key or push button 64 is frictionally pressed onto the upperextension 62 of actuator 42 to provide the manually engageable elementutilizedfor actuation of the switch. A'coil spring 66 also is providedencircling the exterior of the wall defining cavity 28, this springbeing compressed, as in the previous switch embodiments, to urge thepush button 64 away from housing 26 for the switch to assume its normalelectrically open circuit condition.

A disc 150 having'a cup-like cross section, as shown on FIG. 11, isdisposed between the upper end of coil spring 66 and the bottom of pushbutton 64. Disc 150 has a central slot 152 formed therein through whichthe upper extension 62 on actuator 42 passes. Preferably, the slot 152is of a size that the disc 150 frictionally engages with the extension62 so that the disc is retained on the upper end of actuator 42. Thecup-like configuration of disc 150 engages over the upper end of coilspring 66 to guide and retain the upper end of spring Byutilization ofdisc 150 holding spring 66 through frictional engagement of slot 152with extension 62, the switch is kept in fully assembled condition, withor without the presence of a key or push button 64 pressed onto theuppermost end of extension 62 above disc 150. Thus, a selected pushbutton, displaying the desired identifying indicia for the particularswitch, may be placed on the switch extension 62 or removed as desired,and different push buttons interchanged, without freeing the coil spring66. Spring 66 is at all times retained in place and the switch therebyheld in its normal open circuit condition by the presence of cup-likedisc frictionally secured on extension 62 to retain the coil spring.

The actuator 42 in the embidiment of FIG. 11 has an elongated slot 154extending longitudinally thereof. A hollow pin 155 extends transverselypart way across cavity 28 with one end of the pin being retained in oneof the opposed side walls of the cavity 28 in housing 26. This pin 155passes partially into slot 154 from one side and acts to limit theextent of reciprocable movement of actuator 42. However, for reasonswhich will be apparent pin 155 is short enough that an open passagewayremains extending down from slot 154 through the lower end of actuator42. As shown in FIG. 11, the coil spring 66, acting through cup-likedisc 150, while pressing against housing 26 urges actuator 42 to itsuppermost limit where pin 155 is in engagement with the lowermost end ofslot 154.

Of particular importance in the switch embodiment of FIG. 11 is theperfected tube contacting edge portion on actuator 42 which acts againstthe central segment 48 and bight 50 thereof of tube 46 so that the tubeis crimped and pinched as it is stretched over the edge portion wherebythe liquid in tube 56 is parted and consequently the switch normallyexists in a circuit open condition. This edge portion of actuator 42 inFIG. 11 is provided by the lower end of a coil spring 156. The upper endof spring 156 is provided with a loop which is engaged in a hole 158formed in the upper end of the actuator body immediately below the upperextension 62 of the actuator.

The coil spring 156 extends downwardly through the open passagewayextending down from slot 154 past the end of pin 155 and is provided atits lower end with a hook 160. This hook provides the tube contactingedge portion for the switch actuator 42, the hook being engaged with thecentral segment 48 and bight 50 thereof of deformable tube 46.

Thus, when the'switch assumes its normal open circuit condition, asshown in FIG. 11, the coil spring 156 is tensioned by the actuator bodybeing in its uppermost position under the biasing action of externalcoil spring 66. This urges hook 160 on coil spring 156 upwardly so thatthe segment 48 of tube 46 is displaced sufficiently far that the same iscrimped and pinched as it is stretched over the hook 160 whereby theliquid in tube 46 is parted and the switch exists in an open circuitcondition.

In the switch design of FIG. 11, it has been found that provision of thetube contacting edge portion on the switch actuator 42 by utilizing thehook 160 on the end of a coil spring 156 provides a better touch or feelin operation of the switch. This aspect is of particular importance inutilization of switches of this construction in keyboards where switchactuations are achieved by manual depression of selected keys or pushbuttons assembled in groups on the keyboard. Actually, a lesser springforce can be employed in the switch embodiment of FIG. 11 and stillachieve the necessary pinching of the liquid filled tube inaccomplishing a circuit open condition. In this respect it will beappreciated that the tension of exterior spring 66 tends to be reducedor offset by tension of internal spring 156 engaged with segment 48 oftube 46 tending to pull the actuator body and push button 64 down. Alsoof advantage in the FIG. 11 type switch construction, has been thedetermination that a thinner tube wall thickness for tube 46 can beemployed adjacent the point on the tube where it contacts the edgeportion formed by hook 160. This thinning of the tube can be undertakenwithout encountering any loss of life in the tube resulting fromrepeated opening and closing of the switch Thus, the desired sensitivityin switch operation and requisite bounce free opening and closing of anelectrical circuit can be achieved where the tube 46 has the centralsegment 48 ground down over a limited area to thin the wall thickness ofthe tube where the edge portion provided by hook 160 engages the tube topinch it in obtaining circuit opening. Accordingly, this switchconstruction, embodying the spring type tube pinching actuator, hasparticular advantages rendering the switch most ideally suited for codedkeyboard applications, such as the keyboard construction heretoforedescribed.

It can readily be seen that the switch of the instant invention and akeyboard comprising a plurality of the same, substantially solves manyof the problems inherent in prior art devices. The switch includes anextremely uncomplicated switch mechanism capable of crimping a mercuryfilled tube in an efficient manner with a minimum of moving parts.Further, each switch is capable of being encoded or preconditioned totransmit anyone of a large plurality of predetermined electrical codesignals representing informative data. Hence, the switches may becombined with a conductor tape to present a keyboard which hasoutstanding constructional features including simplicity of assembly.

' It is to be understood that the form and'embodiment of the invention,herein shown and described, are to be taken only as preferredrepresentations of the invention and that various changes andmodifications in the arrangement of the components, parts, units, etc.may be resorted to without departing from the spirit of the invention orthe scope of the appended claims.

Iclaim:

1. In a switch,

an elongated, deformable, resilient tube;

' an electrically conductive liquid substantially filling said tube; and

an actuator including a tube contacting edge portion,

said actuator being mounted relative to said tube to laterally displaceat least a central segmental length of the tube to crimp said segmentallength of the tube across said edge portion whereby to part the liquidin said tube and open an electrical circuit intermediate the ends ofsaid tube.

2. In a switch as set forth in claim 1, said edge portion including aknife edge disposed to extend transversely of said tube. I

3. In a switch as set forth in claim 1, said edge portion being providedby a spring member having an end engaged with said central segmentallength of said tube.

4. In a switch as set forth in claim 1, said actuator being reciprocablein a direction laterally of said tube between tube crimping and tubereleasing positions.

5. In a switch as set forth in claim 4, there being included a springoperably coupled to said actuator for yieldably biasing the lattertoward its tube crimping position.

6. In a switch as set forth in claim 4, said actuator including a springmember having an end providing said tube contacting edge portion, saidend being engaged with said central segment of said tube and said springmember being reciprocable as a part of said actuator.

7. In a switch as set forth in claim 4, there being biasing meansprovided to urge said actuator toward its tube crimping position, saidactuator including a manually engageable element operable for manuallyforcing said actuator toward its tube releasing position.

8. A switch comprising:

a housing having a cavity therein;

an elongated, deformable, resilient tube extending through said cavity,the ends of said tube being supported against movement by said housing;an electrically conductive liquid substantially filling said tube; and van actuator supported by the housing for reciprocation along a pathextending through the cavity adjacent the tube, said actuator includinga tube contacting edge portion disposed for contacting and laterallydisplacing at least a central segmental length of the tube within saidcavity when said actuator moves in one direction along said path, saidactuator being movable in said one direction to crimp said length ofsaid tube across said edge portion whereby to part the liquid in saidtube and open an electrical circuit intermediate the ends of said tube.

9. A switch as set forth in claim 8 wherein biasing means is included toyieldably urge said actuator in said.

one direction along said path.

10. A switch as set forth in claim 8 wherein said actuator includes amanually engageable element extending externally of said housing, saidelement being operable for manually forcing said actuator in theopposite direction along said path, there being included an over-centerdevice which normally yieldably resists movement of said actuator insaid opposite direction.

11. A switch as set forth in claim 10 wherein said device comprises acricket spring extending across said path.

12. A switch as set forth in claim 8 wherein said edge portion includesa knife edge disposed to extend transversely of said tube.

13. A switch as set forth in claim 8 wherein said edge portion isdefined by a spring member having an end engaged with said centralsegmental length of said tube.

14. A switch as set forth in claim 8 wherein is included a pair ofcontacts, each contact being disposed in closing relationship to arespective end of the tube and in contacting relationship relative tothe liquid therein, said tube being disposed in a generally U- shapedconfiguration with. the contacts extending outwardly of the housing andgenerally. in the same direction, said edge portion being disposed forcontacting the tube at the bight of the U-shaped configuration.

ing:

a number of elongated contact elements;

a contact element mounting member mounted on the housing adjacent saidcontacts and having a plurality of elongated contact element receivingopenings extending therethrough in the same direction as said contacts,said openings being relatively disposed for simultaneous individualalignment with a corresponding plurality of con-' ductors of anelectrical conducting means which means comprises a plurality ofelongated, side-byside conductors;

said contact elements being disposed in preselected of said openingsrepresenting a predetermined coded combination electronic signal; and van electrically conductive structure mounted on said contact elementmounting member and having a plurality of resilient extensions, saidextensions each overlying one end of one of said contact elementreceiving openings, said extensions each being disposed for yieldablycontacting, in electrical current transmitting relationship, theproximal end of a contact element in the opening which it overlieswhereby to yieldably urge the element toward the opposite end of eachopening, said conductive structure being disposed in electrical currenttransmitting relationship relative to one of said contacts, the othercontact being disposed for contacting one of the conductors of saidconducting means.

16. In an electrical switch keyboard device,

aframe;

an elongated electrical conducting means fixedly mounted on the frameincluding a plurality of generally parallel, laterally spaced conductorssupported by said frame against displacement; and

at least one push-button switch mounted on the frame adjacent theconducting means and said switch including an electrical contact and atleast one electrical contact element, means for yieldably biasing thecontact element toward a corresponding conductor and into electricalcurrent transmitting connection therewith, and. a switching mechanismoperable to make and break an electrical circuit between said contactand said element.

17. In an electrical switch keyboard device as set forth in claim 16said device including a plurality of said switches, each switch havingits contact element located for connection with a different conductor.

18. In an electrical switch keyboard'device as set forth in claim 17,each of said switches having its contact disposed in electricalconnection with a common conductor adapted for providing electricalcurrent to all of the switches simultaneously, one of the elements ofeach switch being disposed in electrical connection with another commonconductor whereby to facilitate detection of a condition when more thanone switch is actuated simultaneously,

1 9. In an electrical switch keyboard device as set forth in claim 16wherein said switch has at least two contact elements, said elementsbeing electrically con 20. In an electrical switch keyboard device asset forth in claim 16 said switch including a contact element mountingmember having a plurality of elongated contact element receivingopenings extending therethrough, said mounting member beingdisposed withits openings each aligned with one of said conductors, each of saidcontact elements being elongated and extending through a correspondingopening.

21. In an electrical switch keyboard device as set forth in claim 20said means for yieldably biasing the elements toward the conductorscomprising an electrically conductive member having a plurality ofresilient extensions, there being a resilient extension overlying theend of each opening remote from said conducting means, said extensionseach being disposed for yieldably contacting the proximal end portion ofa contact element in the corresponding opening and urging the elementthrough its opening and toward a corresponding conductor.

22. In an electricalswitch keyboard device as set forth in claim 20,said member having an opening for each conductor, there being a contactelement in only certain of said openings representing a preselectedcombination of conductors whereby said switch is preconditioned uponactuation to transmit a preselected coded combination electrical signal.

23. A push button switch adapted for transmitting a preselected codedcombination of electrical impulses to an electrical conducting meanshaving a plurality of elongated, side-by-side electrical conductors,said switch comprising:

a pair of electrical contacts;

a switching mechanism operableto make and break an electrical circuitbetween the contacts including a manually'operated actuator element;

a number of elongated contact elements;

a contact element mounting member having a plurality of elongatedcontact element receiving openings extending therethrough, said openingsbeing relatively disposed for simultaneous individual alignment withrespective corresponding conductors, said contact elements beingdisposed in only certain of said openings corresponding to a preselectedcoded combination electrical signal; and

an electrically conductive member mounted on said mounting member andhaving a plurality of resilient extensions, there being a resilientextension overlying one end of each of said openings disposed foryieldably contacting, in electrical current transmitting relationship,the proximal end of a contact element in the corresponding openingwhereby to yieldably urge the element in the direction of its oppositeend and into electrical transmitting relationship with a correspondingconductor,

said conductive member being disposed in electrical current transmittingrelationship relative to one of the contacts of the mechanism,

the other contact of the mechanism being disposed for contacting one ofsaid conductors in current conducting relationship therewith.

24. A switch as set forth in claim 23 wherein said contact elementscomprise diodes.

25. A switch as set forth in claim 23 wherein said mechanism includes anelongated, deformable, resilient tube and an electrically conductiveliquid substantially filling said tube, said contacts being disposed intube closing and liquid contacting relationship at opposite ends of thetube, said actuator element including a tube contacting edge portion,said actuator element being mounted relative to said tube to laterallydisplace at least a central segmental length of the tube to crimp saidsegmental length of the tube across said edge portion whereby to partthe liquid and open an electrical circuit intermediate the ends of saidtube.

26. In a switch, an elongated, deformable, resilient tube; anelectrically conductive liquid substantially filling such tube; anactuator including a tube contacting edge portion, said actuator beingmounted to reciprocate in a direction laterally of said tube betweentube crimping and tube releasing positions by displacing at least acentral segment of the tube and crimping said segment across said edgeportion whereby to part the liquid in said tube and open an electricalcircuit intermediate the ends of said tube; a coil spring urging saidactuator toward its tube crimping position; I a push button separablefrom said actuator and manually operable to force said actuator towardits tube releasing position; and a disc member frictionally retained onsaid actuator beneath said push button to transmit biasing force of saidcoil spring to said actuator. 27. In a switch, an elongated, deformable,resilient tube, an electrically conductive liquid substantially fillingsuch tube; and

an actuator including a tube contacting edge portion, and a second tubecontacting portion disposed on the opposite side of the tube from saidedge portion, said actuator being mounted relative to said tube toreciprocate in a direction laterally of said tube between tube crimpingand tube releasing positions by displacing at least a central segment ofthe tube and crimping said segment across said edge portion whereby topart the liquid in said tube and open an electrical circuit intermediatethe ends of said tube, said second tube contacting portion havingengagement with the tube proximal the crimp therein to assist instraightening the crimp in the tube as the actuator moves toward itstube releasing position.

28. A switch comprising:

a housing having a cavity therein; 7

an elongated, deformable; resilient tube extendin through said cavity,the ends of said tube being supported against movement by said housing;

an electrically conductive liquid substantially filling said tube; and

an actuator supported by the housing for reciprocation along a pathextending through the cavity adjacent to the tube, said actuatorincluding a coil spring having one end thereof connected to andreciprocable as a part of said actuator and the other end provided withhook means engaged with at least a central segmentof said tube withinsaid cavity for laterally isp acmg said central segment when saidactuator moves in one direction along said path, said actuator beingmovable in said one direction to crimp said segment of said tube acrosssaid hook means of said coil spring to part the liquid in said tube andopen an electrical circuit intermediate the ends of said tube.

1. In a switch, an elongated, deformable, resilient tube; anelectrically conductive liquid substantially filling said tube; and anactuator including a tube contacting edge portion, said actuator beingmounted relative to said tube to laterally displace at least a centralsegmental length of the tube to crimp said segmental length of the tubeacross said edge portion whereby to part the liquid in said tube andopen an electrical circuit intermediate the ends of said tube.
 2. In aswitch as set forth in claim 1, said edge portion including a knife edgedisposed to extend transversely of said tube.
 3. In a switch as setforth in claim 1, said edge portion being provided by a spring memberhaving an end engaged with said central segmental length of said tube.4. In a switch as set forth in claim 1, said actuator being reciprocablein a direction laterally of said tube between tube crimping and tubereleasing positions.
 5. In a switch as set forth in claim 4, there beingincluded a spring operably coupled to said actuator for yieldablybiasing the latter toward its tube crimping position.
 6. In a switch asset forth in claim 4, said actuator including a spring member having anend providing said tube contacting edge portion, said end being engagedwith said central segment of said tube and said spring member beingreciprocable as a part of said actuator.
 7. In a switch as set forth inclaim 4, there being biasing means provided to urge said actuator towardits tube crimping position, said actuator including a manuallyengageable element operable for manually forcing said actuator towardits tube releasing position.
 8. A switch comprising: a housing having acavity therein; an elongated, deformable, resilient tube extendingthrough said cavity, the ends of said tube being supported againstmovement by said housing; an electrically conductive liquidsubstantially filling said tube; and an actuator supported by thehousing for reciprocation along a path extending through the cavityadjacent the tube, said actuator including a tube contacting edgeportion disposed for contacting and laterally displacing at least acentral segmental length of the tube within said cavity when saidactuator moves in one direction along said path, said actuator beingmovable in said one direction to crimp said length of said tube acrosssaid edge portion whereby to part the liquid in said tube and open anelectrical circuit intermediate the ends of said tube.
 9. A switch asset forth in claim 8 wherein biasing means is included to yieldably urgesaid actuator in said one direction along said path.
 10. A switch as setforth in claim 8 wherein said actuator includes a manually engageableelement extendinG externally of said housing, said element beingoperable for manually forcing said actuator in the opposite directionalong said path, there being included an over-center device whichnormally yieldably resists movement of said actuator in said oppositedirection.
 11. A switch as set forth in claim 10 wherein said devicecomprises a cricket spring extending across said path.
 12. A switch asset forth in claim 8 wherein said edge portion includes a knife edgedisposed to extend transversely of said tube.
 13. A switch as set forthin claim 8 wherein said edge portion is defined by a spring memberhaving an end engaged with said central segmental length of said tube.14. A switch as set forth in claim 8 wherein is included a pair ofcontacts, each contact being disposed in closing relationship to arespective end of the tube and in contacting relationship relative tothe liquid therein, said tube being disposed in a generally U-shapedconfiguration with the contacts extending outwardly of the housing andgenerally in the same direction, said edge portion being disposed forcontacting the tube at the bight of the U-shaped configuration.
 15. Aswitch as set forth in claim 14 further comprising: a number ofelongated contact elements; a contact element mounting member mounted onthe housing adjacent said contacts and having a plurality of elongatedcontact element receiving openings extending therethrough in the samedirection as said contacts, said openings being relatively disposed forsimultaneous individual alignment with a corresponding plurality ofconductors of an electrical conducting means which means comprises aplurality of elongated, side-by-side conductors; said contact elementsbeing disposed in preselected of said openings representing apredetermined coded combination electronic signal; and an electricallyconductive structure mounted on said contact element mounting member andhaving a plurality of resilient extensions, said extensions eachoverlying one end of one of said contact element receiving openings,said extensions each being disposed for yieldably contacting, inelectrical current transmitting relationship, the proximal end of acontact element in the opening which it overlies whereby to yieldablyurge the element toward the opposite end of each opening, saidconductive structure being disposed in electrical current transmittingrelationship relative to one of said contacts, the other contact beingdisposed for contacting one of the conductors of said conducting means.16. In an electrical switch keyboard device, a frame; an elongatedelectrical conducting means fixedly mounted on the frame including aplurality of generally parallel, laterally spaced conductors supportedby said frame against displacement; and at least one push-button switchmounted on the frame adjacent the conducting means and said switchincluding an electrical contact and at least one electrical contactelement, means for yieldably biasing the contact element toward acorresponding conductor and into electrical current transmittingconnection therewith, and a switching mechanism operable to make andbreak an electrical circuit between said contact and said element. 17.In an electrical switch keyboard device as set forth in claim 16 saiddevice including a plurality of said switches, each switch having itscontact element located for connection with a different conductor. 18.In an electrical switch keyboard device as set forth in claim 17, eachof said switches having its contact disposed in electrical connectionwith a common conductor adapted for providing electrical current to allof the switches simultaneously, one of the elements of each switch beingdisposed in electrical connection with another common conductor wherebyto facilitate detection of a condition when more than one switch isactuated simultaneously.
 19. In an electrical switch keyboard device asset forth in claim 16 wherein said switch has at leasT two contactelements, said elements being electrically connected in parallel andbeing located for connection with a different predetermined conductor,said biasing means being operable for biasing each of the elements ofthe switch toward a corresponding conductor.
 20. In an electrical switchkeyboard device as set forth in claim 16 said switch including a contactelement mounting member having a plurality of elongated contact elementreceiving openings extending therethrough, said mounting member beingdisposed with its openings each aligned with one of said conductors,each of said contact elements being elongated and extending through acorresponding opening.
 21. In an electrical switch keyboard device asset forth in claim 20 said means for yieldably biasing the elementstoward the conductors comprising an electrically conductive memberhaving a plurality of resilient extensions, there being a resilientextension overlying the end of each opening remote from said conductingmeans, said extensions each being disposed for yieldably contacting theproximal end portion of a contact element in the corresponding openingand urging the element through its opening and toward a correspondingconductor.
 22. In an electrical switch keyboard device as set forth inclaim 20, said member having an opening for each conductor, there beinga contact element in only certain of said openings representing apreselected combination of conductors whereby said switch ispreconditioned upon actuation to transmit a preselected codedcombination electrical signal.
 23. A push button switch adapted fortransmitting a preselected coded combination of electrical impulses toan electrical conducting means having a plurality of elongated,side-by-side electrical conductors, said switch comprising: a pair ofelectrical contacts; a switching mechanism operable to make and break anelectrical circuit between the contacts including a manually operatedactuator element; a number of elongated contact elements; a contactelement mounting member having a plurality of elongated contact elementreceiving openings extending therethrough, said openings beingrelatively disposed for simultaneous individual alignment withrespective corresponding conductors, said contact elements beingdisposed in only certain of said openings corresponding to a preselectedcoded combination electrical signal; and an electrically conductivemember mounted on said mounting member and having a plurality ofresilient extensions, there being a resilient extension overlying oneend of each of said openings disposed for yieldably contacting, inelectrical current transmitting relationship, the proximal end of acontact element in the corresponding opening whereby to yieldably urgethe element in the direction of its opposite end and into electricaltransmitting relationship with a corresponding conductor, saidconductive member being disposed in electrical current transmittingrelationship relative to one of the contacts of the mechanism, the othercontact of the mechanism being disposed for contacting one of saidconductors in current conducting relationship therewith.
 24. A switch asset forth in claim 23 wherein said contact elements comprise diodes. 25.A switch as set forth in claim 23 wherein said mechanism includes anelongated, deformable, resilient tube and an electrically conductiveliquid substantially filling said tube, said contacts being disposed intube closing and liquid contacting relationship at opposite ends of thetube, said actuator element including a tube contacting edge portion,said actuator element being mounted relative to said tube to laterallydisplace at least a central segmental length of the tube to crimp saidsegmental length of the tube across said edge portion whereby to partthe liquid and open an electrical circuit intermediate the ends of saidtube.
 26. In a switch, an elongated, deformable, resilient tube; anelectrically conductive lIquid substantially filling such tube; anactuator including a tube contacting edge portion, said actuator beingmounted to reciprocate in a direction laterally of said tube betweentube crimping and tube releasing positions by displacing at least acentral segment of the tube and crimping said segment across said edgeportion whereby to part the liquid in said tube and open an electricalcircuit intermediate the ends of said tube; a coil spring urging saidactuator toward its tube crimping position; a push button separable fromsaid actuator and manually operable to force said actuator toward itstube releasing position; and a disc member frictionally retained on saidactuator beneath said push button to transmit biasing force of said coilspring to said actuator.
 27. In a switch, an elongated, deformable,resilient tube, an electrically conductive liquid substantially fillingsuch tube; and an actuator including a tube contacting edge portion, anda second tube contacting portion disposed on the opposite side of thetube from said edge portion, said actuator being mounted relative tosaid tube to reciprocate in a direction laterally of said tube betweentube crimping and tube releasing positions by displacing at least acentral segment of the tube and crimping said segment across said edgeportion whereby to part the liquid in said tube and open an electricalcircuit intermediate the ends of said tube, said second tube contactingportion having engagement with the tube proximal the crimp therein toassist in straightening the crimp in the tube as the actuator movestoward its tube releasing position.
 28. A switch comprising: a housinghaving a cavity therein; an elongated, deformable, resilient tubeextending through said cavity, the ends of said tube being supportedagainst movement by said housing; an electrically conductive liquidsubstantially filling said tube; and an actuator supported by thehousing for reciprocation along a path extending through the cavityadjacent to the tube, said actuator including a coil spring having oneend thereof connected to and reciprocable as a part of said actuator andthe other end provided with hook means engaged with at least a centralsegment of said tube within said cavity for laterally displacing saidcentral segment when said actuator moves in one direction along saidpath, said actuator being movable in said one direction to crimp saidsegment of said tube across said hook means of said coil spring to partthe liquid in said tube and open an electrical circuit intermediate theends of said tube.